X-ray computed tomography (CT) is a technology for reconstructing a cross section of a detected object by utilizing the computer technology, to obtain a tomographic image. In this technique, the ray that passes through the detected object is collected by a computer and an image is reconstructed by using a certain algorithm, based on different ray absorptivity and transmissivity for each portion of the detected object when the ray passes through the detected object.
There are many scanning modes for the existing CT devices. With the rotational speed, the spatial resolution and the width of the detection for the device being increased and the requirement on the radiation dose for scanning becoming strict, the tilted helical scan mode has been widely used due to the reduced radiation damage of the X-ray on certain special portions of a human body and the positive effect on the scan imaging for a curvilinear anatomical structure.
According to the geometrical structure of the tilted scan, the motion trajectory of the X-ray source relative to the object is a beveled helical structure. Therefore, artifacts may appear when reconstructing an image using a conventional helical reconstruction method. Generally, data correction, such as interpolation or smoothing, has to be performed before the image reconstruction. However, this data correction may contaminate the raw data in a certain degree, thereby affecting the quality of the final reconstructed image.